Date:   Wed, 25 Sep 2019 11:43:14 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH 2/2] devfreq: Rename df->previous_freq to df->cur_freq

The vast majority of code uses df->previous_freq to get the current
frequency of the devfreq device, not the previous one. Rename the
struct field to reflect this.

Add a comment to devfreq_update_stats() to make clear that df->cur_freq
must only be updated after calling this function in the context of a
frequency transition.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 drivers/devfreq/devfreq.c            | 28 ++++++++++++++++------------
 drivers/devfreq/governor_passive.c   |  6 +++---
 drivers/devfreq/governor_userspace.c |  2 +-
 drivers/devfreq/tegra20-devfreq.c    |  2 +-
 drivers/devfreq/tegra30-devfreq.c    |  2 +-
 include/linux/devfreq.h              |  4 ++--
 include/trace/events/devfreq.h       |  2 +-
 7 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index fb4318d59aa9..bf42130bb4ec 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -154,6 +154,10 @@ static int set_freq_table(struct devfreq *devfreq)
  * devfreq_update_stats() - Update statistics of devfreq behavior
  * @devfreq:	the devfreq instance
  * @freq:	the update target frequency
+ *
+ * If the function is called in the context of a frequency transition
+ * it expects df->cur_freq to contain the value *before* the transition.
+ * The field must only be updated after calling devfreq_update_stats().
  */
 int devfreq_update_stats(struct devfreq *devfreq, unsigned long freq)
 {
@@ -162,11 +166,11 @@ int devfreq_update_stats(struct devfreq *devfreq, unsigned long freq)
 
 	cur_time = jiffies;
 
-	/* Immediately exit if previous_freq is not initialized yet. */
-	if (!devfreq->previous_freq)
+	/* Immediately exit if cur_freq is not initialized yet. */
+	if (!devfreq->cur_freq)
 		goto out;
 
-	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
+	prev_lev = devfreq_get_freq_level(devfreq, devfreq->cur_freq);
 	if (prev_lev < 0) {
 		ret = prev_lev;
 		goto out;
@@ -295,7 +299,7 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
 	if (devfreq->profile->get_cur_freq)
 		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
 	else
-		cur_freq = devfreq->previous_freq;
+		cur_freq = devfreq->cur_freq;
 
 	freqs.old = cur_freq;
 	freqs.new = new_freq;
@@ -315,7 +319,7 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
 		dev_err(&devfreq->dev,
 			"Couldn't update frequency transition information.\n");
 
-	devfreq->previous_freq = new_freq;
+	devfreq->cur_freq = new_freq;
 
 	if (devfreq->suspend_freq)
 		devfreq->resume_freq = cur_freq;
@@ -450,7 +454,7 @@ void devfreq_monitor_suspend(struct devfreq *devfreq)
 		return;
 	}
 
-	devfreq_update_stats(devfreq, devfreq->previous_freq);
+	devfreq_update_stats(devfreq, devfreq->cur_freq);
 	devfreq->stop_polling = true;
 	mutex_unlock(&devfreq->lock);
 	cancel_delayed_work_sync(&devfreq->work);
@@ -483,7 +487,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
 
 	if (devfreq->profile->get_cur_freq &&
 		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
-		devfreq->previous_freq = freq;
+		devfreq->cur_freq = freq;
 
 out:
 	mutex_unlock(&devfreq->lock);
@@ -644,7 +648,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	devfreq->dev.release = devfreq_dev_release;
 	devfreq->profile = profile;
 	strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
-	devfreq->previous_freq = profile->initial_freq;
+	devfreq->cur_freq = profile->initial_freq;
 	devfreq->last_status.current_frequency = profile->initial_freq;
 	devfreq->data = data;
 	devfreq->nb.notifier_call = devfreq_notifier_call;
@@ -1235,14 +1239,14 @@ static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
 		return sprintf(buf, "%lu\n", freq);
 
-	return sprintf(buf, "%lu\n", devfreq->previous_freq);
+	return sprintf(buf, "%lu\n", devfreq->cur_freq);
 }
 static DEVICE_ATTR_RO(cur_freq);
 
 static ssize_t target_freq_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
+	return sprintf(buf, "%lu\n", to_devfreq(dev)->cur_freq);
 }
 static DEVICE_ATTR_RO(target_freq);
 
@@ -1398,7 +1402,7 @@ static ssize_t trans_stat_show(struct device *dev,
 	unsigned int max_state = devfreq->profile->max_state;
 
 	if (!devfreq->stop_polling &&
-			devfreq_update_stats(devfreq, devfreq->previous_freq))
+			devfreq_update_stats(devfreq, devfreq->cur_freq))
 		return 0;
 	if (max_state == 0)
 		return sprintf(buf, "Not Supported.\n");
@@ -1413,7 +1417,7 @@ static ssize_t trans_stat_show(struct device *dev,
 
 	for (i = 0; i < max_state; i++) {
 		if (devfreq->profile->freq_table[i]
-					== devfreq->previous_freq) {
+					== devfreq->cur_freq) {
 			len += sprintf(buf + len, "*");
 		} else {
 			len += sprintf(buf + len, " ");
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
index 1c746b96d3db..2d818eaceb39 100644
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -114,7 +114,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
 		dev_err(&devfreq->dev,
 			"Couldn't update frequency transition information.\n");
 
-	devfreq->previous_freq = freq;
+	devfreq->cur_freq = freq;
 
 out:
 	mutex_unlock(&devfreq->lock);
@@ -134,11 +134,11 @@ static int devfreq_passive_notifier_call(struct notifier_block *nb,
 
 	switch (event) {
 	case DEVFREQ_PRECHANGE:
-		if (parent->previous_freq > freq)
+		if (parent->cur_freq > freq)
 			update_devfreq_passive(devfreq, freq);
 		break;
 	case DEVFREQ_POSTCHANGE:
-		if (parent->previous_freq < freq)
+		if (parent->cur_freq < freq)
 			update_devfreq_passive(devfreq, freq);
 		break;
 	}
diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
index af94942fcf95..566b8d1f0c17 100644
--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -26,7 +26,7 @@ static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
 	if (data->valid)
 		*freq = data->user_frequency;
 	else
-		*freq = df->previous_freq; /* No user freq specified yet */
+		*freq = df->cur_freq; /* No user freq specified yet */
 
 	return 0;
 }
diff --git a/drivers/devfreq/tegra20-devfreq.c b/drivers/devfreq/tegra20-devfreq.c
index ff82bac9ee4e..f99bd6557df5 100644
--- a/drivers/devfreq/tegra20-devfreq.c
+++ b/drivers/devfreq/tegra20-devfreq.c
@@ -61,7 +61,7 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
 	return 0;
 
 restore_min_rate:
-	clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq);
+	clk_set_min_rate(tegra->emc_clock, devfreq->cur_freq);
 
 	return err;
 }
diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index 536273a811fe..7b3bf7a0b15f 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -474,7 +474,7 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
 	return 0;
 
 restore_min_rate:
-	clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq);
+	clk_set_min_rate(tegra->emc_clock, devfreq->cur_freq);
 
 	return err;
 }
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 2bae9ed3c783..21d0108df4c5 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -120,7 +120,7 @@ struct devfreq_dev_profile {
  *		reevaluate operable frequencies. Devfreq users may use
  *		devfreq.nb to the corresponding register notifier call chain.
  * @work:	delayed work for load monitoring.
- * @previous_freq:	previously configured frequency value.
+ * @cur_freq:	the current frequency.
  * @data:	Private data of the governor. The devfreq framework does not
  *		touch this.
  * @min_freq:	Limit minimum frequency requested by user (0: none)
@@ -156,7 +156,7 @@ struct devfreq {
 	struct notifier_block nb;
 	struct delayed_work work;
 
-	unsigned long previous_freq;
+	unsigned long cur_freq;
 	struct devfreq_dev_status last_status;
 
 	void *data; /* private data for governors */
diff --git a/include/trace/events/devfreq.h b/include/trace/events/devfreq.h
index cf5b8772175d..916cfaed5489 100644
--- a/include/trace/events/devfreq.h
+++ b/include/trace/events/devfreq.h
@@ -22,7 +22,7 @@ TRACE_EVENT(devfreq_monitor,
 	),
 
 	TP_fast_assign(
-		__entry->freq = devfreq->previous_freq;
+		__entry->freq = devfreq->cur_freq;
 		__entry->busy_time = devfreq->last_status.busy_time;
 		__entry->total_time = devfreq->last_status.total_time;
 		__entry->polling_ms = devfreq->profile->polling_ms;
-- 
2.23.0.444.g18eeb5a265-goog

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